<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>删除</button>
    <ul>
        <li>熊大</li>
        <li>熊二</li>
        <li>佩奇</li>
    </ul>
    <script>
        //1.获取元素
        var btn=document.querySelector('button');
        var ul=document.querySelector('ul');
        //2.删除元素  node.removeChild(child)
        btn.onclick=function(){
           if(ul.children.length===0)
           {
               this.disabled=true;
           }
           else{
            ul.removeChild(ul.children[0]);
           }
        }
      
    
    </script>
</body>
</html>